1. Field of the Invention
The present invention relates to a camera switchable between a natural light or daylight photography mode (wherein the shutter speed (and the diaphragm aperture in the case of a programmed shutter) is automatically controlled in accordance with the light from an object to be photographed under the illumination of natural light thereby providing a proper exposure), and a flash photography mode (wherein an electronic flash is fired and the shutter speed (and the diaphragm aperture in the case of a programmed shutter) is controlled to values suitable for flash photography).
2. Description of the Prior Arts
A device is known which warns blur-occurring when a shutter speed automatically controlled in accordance with an object's brightness is anticipated to be so low as to cause blur in the picture due to the movement of the hand-held camera upon photographing. The blur occurs more frequently in photography with a telephoto lens than in photography with a standard lens. A Japanese Laid-Open Patent Publication Sho No. 52-135728 discloses a warning device which is adapted for use with a camera having an objective lens with its focal length being selectively changed in substance, and in which the reference shutter speed for the warning of the blur-occurring is automatically changed in conjunction with selection of the focal length of the objective lens. However, since the disclosed warning device only makes warning of a blur-occurring shutter speed, the user, in response to the warning, must change the diaphragm setting to a larger aperture to obtain a higher shutter speed or switch the camera to enable flash photography.
U.S. Pat. Nos. 4,112,442 and 3,504,604 show photography mode switching devices which switch camera operational condition from the natural light photography mode to the flash photography mode when the brightness of an object or scene to be photographed is lower than a given reference level. In such switching devices, however, the reference level for switching to the flash photography mode can not be changed in conjunction with change of the focal length of an objective lens.